Electron tube and circuit employing it



` Sept. 24, 1940. A G, CLAV|ER Er AL 2,215,779

ELECTHON TUBE ND CIRCUIT EMPLOYING IT Original Filed May 27, 1938patented Sept. 424, 11940 UNITED STATES ELECTRON TUBE AND CIRCUITEMPLOYIN G IT Andre Gabriel Clavier and Ernest Rosts, Paris, France,assignors to International Standard Electric CorporatiomNew York, N. Y.

Original application May 27, 1938, Serial No. 210,332. Divided and thisapplicationJune 9,

1939, Serial No. 278,205. n France May 6 Claims.

The present invention relates to new electron tubes and theirutilisation and to circuitsemployed with such tubes.

` This application is a division of our copending application Serial No.210,332, led May 27, 1938.

One of the objects of the invention is to improve the output andoperation of ultra-high frequenoy systems, for example, employingfrequencies corresponding to wave lengths ofthe order of the decimeter,the centimeter or even of values considerably lower as Well asfrequencies of higher wave length.

In order to understand the nature of the present invention, it seemswell to make some remarks with regard to the output of the electrontubes employed in particular as oscillators.

The output of the normal oscillator or amplifier tubes, that is to say,those in which the time of transit of the electrons remains short withrespect to the period of the oscillation, is all the greater if thealternating tension between electrodes is a fraction higher than thedirect tension in the source of supply (the output impedance beingassumed to be ohmic).

By applying this reasoning to tubes in which the time of transitof theelectrons is comparable to the period, there will be found a doublelimitation of the outputof these tubes. The first is the l diiculty inachieving output circuits of a sucient impedance to obtain these hightensions. This limitation is not directly bound up with the use ofelectronic oscillators. It is simply due to the high `frequencies whichit is attempted to use. .The second on the other hand is directlyconnected with the method of opera-tion of` the' tubes. One of theconditions necessary for the operation of the present tubes is that thetime of transit of the electrons should not depart too much from a meansuitable value related in a xed manner to the period. Now, this type oftransit depends upon `the value of the alterhating tension superposed onthe direct tension. inasmuch as the high frequency tension is small withrespect to the direct tension, `the above condition is fuliilled. If itbecomes comparable with l the direct tension it `considerably modiiiesthe time of transit of the electrons which leave at different moments inthe period, and thus limits the amplitude of the oscillation. It .willconsequently be seen that the high frequency tension must always remainsmall in proportion to the direct tension. Inmaccordance with thisreasoning the output of the electron tubes will thus 55 seemtheoretically limited to low values.

It is found, however, `that the condition offered by normal tubes ofonly being able to lead to a good output if the alternating highfrequency tension becomes comparable with the direct tension is notinevitable in the case of electronic oscillators. This will be seen byconsidering not the output but the losses in the tubes and by seekingfor the condition which leads to the is negligible the two expressionsare equivalent since in this `case the speed of the electrons arrivingon the positive electrode is equal to the tension of this electrode.

In the case in which the time of transit is comparable with the periodthe speed of the eleci trons arriving on an electrode is not always thatcorresponding to the potential of this electrode. This speed maybehigher or lower than the speed corresponding to the tension of thiselectrode. The difference of speed in proportion to the case of anegligible time of transit may become great, in spite of a low highfrequency tension, in the case in which the electrons oscillate severaltimes in thehigh frequency fields before arriving on the electrode. Itiwill be seen that the instantaneouslosses in such a tube are no longergiven by the `product ofthe instantaneous current by the instantaneoustension. They may be greater or smaller. This difference is supplied orabsorbed by the oscillatory circuit. The t output of the tube thus nolonger depends in` the same way on the high frequency tensionwon theterminals of the load. The output is increased if the speed of theelectrons on arrival on the electrode is smaller than that correspondingto the potential electrode; it -is reduced if the speed is increased.

The present invention provides arrangements in which the electrons aresystematically slowed down by one or more fields of high frequency, f

and thus supply `energy in one or` more oscillatory circuits, losing itthemselves.

The present invention in accordance with one of its aspects thus permitsthe said limitations to be overcome; among others it provides anelection these arrangements are such that the retardation of theelectrons is produced in the system repeatedly under the action of thesa-me high frequency field, or fields, so as to increase the totalenergy given by the electrons concerned to the oscillatory circuit.

In accordance with another feature of the arrangement underconsideration, the retardation of the mean speed of the electrons isproduced by the magnetic or electro-magnetic high frequency fieldsustained by the energy given up by the slowing down of the averagespeed of the electrons.

The invention is not limited to the generation of ultra-high frequencywaves and the tubes described here may be adapted to be employed for thegeneration amplification or detection as well as for various otherapplications, such for example, as in oscillographic systems ortelevision systems, or for measuring apparatus.

The invention will be explained in detail in the case of the generationof ultra-high frequency waves, and indications will be given with regardto its employ in other elds.

The present invention will be better understood by means of thefollowing description based on the attached drawing in which:

Fig. 1 shows a particular embodiment of the invention in which theelectronic bundle advances in a zig-zag path; and

Fig. 2 is a section of the guide electrode structure of the device ofFig. 1, along the line 4 4.

Fig. 1 represents another embodiment of a device for the systematicretardation of the electrons comprising an evacuated envelope E in whichare arranged an electron gun G, two pairs of deilecting plates D1, D2operating in the ordinary way to produce and dene an electron bundle andtwo pairs of metal retarding plates R1, R2 respectively associated withmetallic reecting electrodes P1 and P2. Fig. 2 shows a section of thisgure along the line Fig. 1. The oscillatory output circuit O composed,for example, of a Lecher line is connected to each pair of retardingelectrodes, and its middle point is connected to the electron gun G. Thereflecting electrodes are connected to a source S3 of potential negativewith respect to the cathode. Targets C1, C2 are placed on the two Lecherwires at the en'dof the structures'.

YThe bundle of electrons F passes between the electrodes R1 parallel tothe surface of these electrodes, passes through the interval between theelectrodes R1 and the electrodes R2 at a certain angle different from90, then passes between the electrodes R2. On its approach to thereflecting electrode P2 at the outer edges of the electrodes R2 thebundle is returned to the space between R2 as shown, again passesbetween the plates R1 and is returned by the electrode P1. The bundlethus advances in zig-zag along the structure in order finally to strikeone of the targets C1 or C2.

A tension U cos wt is assumed to exist between the pairs of electrodesR1 and R2. If the time between the two successive passages through theinterval between the electrodes R1 and R2 is a half period the electrodewill be retarded on each journey if it has been retarded on the rstjourney. If the form of the electrodes is suitably chosen we then nd inconsequence of considerations similar to those given for the tube ofFig. 1 that the electrons will be retarded on the average and willconsequently supply energy to the oscillatory circuit composed of thetuned transmission line O.

If the form of the reflecting electrode P1 or P2 is suitably chosen theelectro-static eld between the main electrode and the reecting electrodeis such that it forms an electronic lens assisting to maintain theconcentration of the electron bundle. This eld is representedschematically in Fig. 2 by means of its equipotential lines.

When we produce an oscillator device by the means which have just beendescribed we have at our disposal a negative resistance effect which canbe utilised in the amplification of electrical oscillations, forexample, of the same order of magnitude as that of the oscillationswhich can be produced by the tube, when the conditions of operation areadjusted to be outside the range of conditions in which self-oscillationoccurs.

In the case in which it is desired to employ such tubes as modulatedoscillation generators it is possible to provide inside the tubes whichhave just been described electrodes having an influence on either theintensity or the direction of the electronic bundle or bundles employed.

Other arrangements within the spirit of the `invention and within thescope of the appended claims will be apparent to those versed in theart.,

What is claimed is 1. Electron tube arrangement comprising a source ofelectrons, a high frequency oscillatory circuit comprising co-extensiveelongated electrode surfaces, and means for directing the electrons fromsaid source in a sinuous path over said electrode surfaces and in thefield thereof for the repeated retardation of the electrons and for themaintenance of oscillations in said oscillatory circuit.

2. Electron tube arrangement comprising a source of electrons, a pair ofelectrodes each comprising two substantially parallel plates, therespective plates of' one of said electrodes lying alongside andcoplanar with the respective plates of the o'ther of said electrodes, ahigh frequency oscillatory circuit connected with said electrodes andmeans for directing the electrons from said source in a zig-Zag pathentering the electrodes alternately for the maintenance of oscillationsin said oscillatory circuit by the repeated retardation of theelectrons.

3. Electron tube arrangement according to claim 2, includingelectrostatic means at the outer edges of said electrodes for reflectingthe electrons entering said electrodes.

4. Electron tube arrangement according to claim 2 including convergingreflecting electrodes bounding the zig-Zag electron path.

5. An electron tube oscillator comprising two pairs of spaced plateswith the spaces between the plates in alignment and means associatedtherewith for setting up a high frequency field between said pairs ofplates, means for directing a bundle of electrons between said pairs ofplates in succession in zig-zag fashion for the repeated retardation ofsaid electrons by the action of the eld between said plates, and meansfor utilizing the energy derived from the retardation of said electronsfor the maintenance of electrical oscillations.

6. An electron tube oscillator according to claim 2 wherein said pairsof electrodes are of decreasing width in the direction of travel of saidelectrons whereby the amplitude of the zig-zag path decreases with thedecreasing speed of the electrons.

ANDRE GABRIEL CLAVIER.

ERNEST RosTs.

